This invention relates to an electronic musical instrument equipped with a device capable of imparting various tonal effects including an attack pitch control, touch response, vibrato and slur, etc.
The attack pitch control is a control for changing the tone pitch repeatedly or gradually during a short period of time at the beginning of sounding of the tone. The technique of the attack pitch control is employed in the electronic musical instrument for simulating turbulence in the pitch at the beginning of sounding of a tone such, for example, as turbulence in the pitch at the beginning of playing a wind instrument. In the attack pitch control in the prior art electronic musical instrument, control factors such as the initial depth of pitch deviation remain unchanged once they have been set by selection switches, unless the setting is subsequently changed. The prior art electronic musical instrument, therefore, can provide only an attack pitch control which is poor in expression. An example of the prior art attack pitch control is disclosed in the specification of U.S. Pat. No. 4,189,972. The disclosed control, however, is a simple and monotonous one according to which the attack pitch control always starts from a pitch which is below a nominal pitch by a predetermined cent value and thereafter gradually approaches the nominal pitch.
The above-mentioned U.S. Pat. No. 4,189,972 discloses also a vibrato device and a delay vibrato device. In the disclosed devices, however, the attack pitch control device in no way is associated with the vibrato device or the delay vibrato device but the respective tonal effects are individually selected to be imparted to the tone by individual selection switches. For imparting a richer expression to vibrato or delay vibrato, it is desired that the attack pitch control should be automatically added in association with vibrato or delay vibrato. No such effect imparting device has heretofore been known.
The above-mentioned U.S. Pat. No. 4,189,972 further discloses the art of generating, in digital, a modulating signal for vibrato or delay vibrato and processing this signal. More specifically, there is disclosed an art of oscillating a clock of a variable frequency by a voltage-controlled type oscillator (hereinafter referred to as "VCO"), counting up or down contents of a counter one by one and forming a digital modulating signal. In the disclosed art, the vibrato frequency is controlled by variably adjusting the oscillation frequency of the VCO. The vibrato depth is controlled by suitably shifting an output signal of the counter by a shift circuit. This disclosed device has the disadvantage that the provision of the VCO for variably adjusting the vibrato frequency necessitates a relatively large-scale circuit construction. Besides, the requirement in this device for conducting the depth control by numerical shifting results in a complicated circuit construction of the shift circuit. Since the number obtained by shifting of a binary number is limited to a number which is 2.sup.n of the original number, a shift circuit of a simple construction can perform only a simple depth control and a complicated shift circuit having a function to add or subtract various shifted numerical values must be employed for obtaining a complicated depth control. Alternatively, it is conceivable to use a multiplier instead of a shift circuit for effecting the depth control. This, however, will further complicate the circuit construction.
There are two types of tone control by touch response which is well known in the art. One is an initial touch control according to which a key touch at the beginning of key depression (i.e., initial touch) is detected in accordance with a key depressing force, speed of the key depression or other factors and the tone pitch, tone level and tone color are controlled in accordance with this initial touch. Another is an after touch control according to which a key touch (i.e. after touch) is detected in accordance with a key depressing force or depth of the key depression in sustained state of key depression and the tone pitch, tone level and tone color are controlled in accordance with this after touch. For simulating performances by an electronic musical instrument to performances by a natural musical instrument, it is desirable to perform both of the above described touch response controls. For realizing this, the prior art electronic musical instrument required touch sensors for both of the controls resulting in requirement of a keyboard of an extremely complicated construction accompanied by a high manufacturing cost.
There is also known an electronic musical instrument capable of imparting a portamento effect. The portamento effect in the prior art electronic musical instrument, however, is imparted only when this effect has been selected by a manual selection switch. Accordingly, the portamento effect is imparted whenever a key is depressed and this often gives rather a monotonous impression to the audience. Alternatively, there is a device in which the portamento effect is selectively imparted by operating a foot switch. This device is cumbersome because the foot switch must be operated each time the portamento effect is to be imparted.
For imparting, in an electronic musical instrument of a digital processing type, various tonal effects such as the attack pitch control, vibrato, delay vibrato, portamento and touch response, control amounts of various control elements such as tone level, the speed of modulation and the depth of modulation must be given in a digital amount. For this purpose, a digital setter for directly setting digital data corresponding to one of the control elements is provided inidividually for each of the control elements. For obtaining sufficient range and resolution of the control amounts in such digital setter, a great number of contacts are required. The prior art electronic musical instrument in which a number of such digital setters must be provided for the respective control elements requires an increased cost of manufacture, an increased number of wiring and a broader space for mounting such digital setters. It is conceivable for overcoming the above problem to use an analog voltage setting potentiometer as the data setter and obtaining digital data by digitally converting the output voltage of this potentiometer. Provision of an analog to digital converter for each potentiometer, however, inevitably necessitates a higher cost of manufacture and a broader circuit space. It is therefore desired to realize a digital data setting device capable of overcoming the above described problem.